Method and apparatus for forming bag closures



June 20, 1967 G. CAMERINI METHOD AND APPARATUS FOR FORMING BAG CLOSURES Filed May 18, 1964 '7 Sheets-Sheet 1 INVEN'I'ORv June 20, 1967 3. CAMERINI 3,326,094

METHOD AND APPARATUS FOR FORMING BAG CLOSURES Filed May 18, 1964 7 Sheets-Sheet 2;

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METHOD AND APPARATUS FOR FORMING BAG CLOSURES Filed May 18, 1964 '7 Sheets-Sheet 5 INVENTOR.

June 20, 1967 G. CAMERINI 3,326,094

METHOD AND APPARATUS FOR FORMING BAG CLOSURE-1S Filed May 18, 1964 '7 Sheets-Sheet Z/mmwwkm,

flw m f 25m United States Patent METHOD AND APPARATUS FGR FORMING BAG CLOSURES Giorgio Camerini, Milan, Italy, assignor to Natro-Cellulosa, S.p.A., Milan, Italy, a corporation of Italy Filed May 18, 1964, Ser. No. 368,162

Claims priority, application Italy, May 20, 1963,

10,358/63 9 Claims. (Cl. 9328) This invention relates to the manufacture of bags, and is particularly suited to the production of bags made from plastic or similar non-rigid, non-creasable sheet materials and having end closures formed of side and corner closure flaps which are folded inwardly and secured in superposed relation. Such bags are used extensively in the packaging of granular and powdered materials. Also, the particular end closure construction of these bags may be modified to provide a valve effect which adapts them for use in connection with automatic packaging techniques. Valve bags of this type are shown and described in U. S. Patent 3,117,711, issued Jan. 14, 1964.

The present invention is particularly directed to that portion of the bag manufacturing process which involves the opening of a side -flap portion at the end or ends of a flattened tubular bag blank; and sealing or securing the marginal edges of the thus formed folded in corner flaps to the under surfaces of the side flaps.

There are several well known techniques which have been used successfully to provide automatic opening or separation of the side flap portions of flattened tubular bag blanks and for preparing the remaining end portions of the blanks for the subsequent operations of pasting, closing and pressing. However, all these previously known techniques make use of the stiffness and creasing properties of the material of the bag blank, whereby the material will retain any folded configuration imposed upon it. While such prior art techniques were adequate to form bags of materials such as paper and the like, they have been found to be completely inadequate to the manufacture of bags from such non-creasable and relatively limp materials as plastic sheeting. The prior art techniques for forming and end construction from bag blanks made of paper involved the steps of folding :and creasing one or both ends of the blank so that it extended upwardly. Thereafter a separating element was caused to enter between the side flap portions of the upwardly extending end to separate and fold these side flap portions in outward directions. Simultaneously, the corner flaps would be bent down inwardly and creased into place. \Because the paper material of the bag blank possesses creasability and a certain amount of rigidity, each step in the end forming operation could be performed independently; and the blank would by itself retain the characteristics imparted to it by the preceding steps.

In addition to the above, the apparatus used in conjunction with the prior art bag manufacturing techniques did not, when used in conjunction with paper bag blanks, encounter any problem in connection with feeding and transferring the blanks from one station to the next. Because of the rigidity of the paper material employed, the tubular blank could be held at any single point along its longitudinal edge and dragged without becoming distorted during the transferring operation. In most cases the tubular paper bag blanks are held along their longitudinal edge by means of pincers located at a point corresponding to the center line of the 'blank. These pincers move along among 3,326,094 Patented June 20, 1967 the means for folding 'and opening the end or ends of the blank without hampering or complicating the structure of these means.

When a bag material is employed which does not retain its shape or which has a very low rigidity as, for example, highly plastified material, the above-described folding operations cannot be carried out by the conventional means.

Since plastic materials do not retain creases and folds and since they have a very low rigidity it has become necessary to solve problems which did not exist in the paper bag industry. In order that the side and corner fiaps be made to assume and keep their desired positions, i.e., open for the side flaps and inwardly folded for the corner flaps, the bag forming apparatus must be provided; firstly, with means capable of accompanying the side flaps during the full side flap folding step; and secondly, with means capable of securing (as by welding), the corner flaps to the under surfaces of the side flaps. This securing operation should also produce fold lines along which the side flaps are thereafter inwardly folded to complete the bottom closure. Also, during the closing of the bag bottom, the displacement of the corner flaps from their desired position must be avoided in order to assure a tight sealing of the finished bag.

It is one object of the present invention to provide a method and means for opening the side flap portions of at least one end of a flattened tubular bag blank or nonrigid plastic or similar sheet material; and to secure the marginal edges of the corner flaps to the under surfaces of the side flaps.

Another object of the present invention is to provide an apparatus capable of individually and without distortion transferring tubular bag blanks of non-rigid, noncreasable plastic material from a feeding device to a folding station.

A further object is to provide an apparatus having means capable of automatically arresting the sealing of the corner flaps to the under surfaces of the side flaps whenever a tubular bag blank assumes an improper position in the folding station.

These and other objects are attained according to the present invention by positioning a tubular bag blank into an opening station and causing suction plates in said opening station to move over the edge flap portions of the ends of the blank and thence in a relatively rotational pattern whereby one edge flap portion is caused to be separated from the other and folded about a preselected fold line along the axis of such rotational pattern; and while holding the edge flap portions in such position, causing the inwardly folded corner flaps to be secured (preferably by welding) along marginal lines to the edge flaps.

In the illustrative embodiment one suction plate is stationary while the other is caused to move through a prescribed translational and rotational pattern. The mechanism for producing this movement includes a parallelogram type support linkage located at either end of the movable plate. The support linkages each include a fixed pivot, a front connecting arm extending between the fixed pivot and a point on the front edge of the movable plate, a crank arm independently pivoted at the fixed pivot, and a rear connecting arm extending between the outer point of the crank arm and a rearward point on the movable plate.

By rotating the front connecting arms the plate is moved translationally until its front edge is brought up against the desired line of fold of the side flap of the bag blank. The crank arm is then rotated, causing the plate to roa v.5 tate about its front edge and the line of fold so as to become positioned in face to face relationship to the stationary plate with the suction surfaces of the plates sandwiching the end of the blank between them. The suction effect of the movable plate causes one side flap to adhere to it so that when the crank arm is again moved in the opposite direction this side flap is caused to rotate with the movable plate about the desired line of fold. The suction effect produced by the stationary plate produces a retentive effect upon the opposite side flap causing it to adhere thereto so that it remains in place during the folding operation. The folding operation of itself causes the corner flaps to fold inwardly so that they may be readily secured along their marginal edges (as by heat welding) to the side flaps. The stationary and movable plates are provided with electrode elements which extend parallel to the line of rotation or front edge of the movable plate. A welding unit is provided and includes cooperative electrodes which are caused to swing down upon the plate electrode elements when the plates are in open position so that the side and corner flaps may be heat sealed along their marginal edges. If desired, the various electrodes may be lengthened to cause heat formed creases to be impressed along the entire length of the side flap fold lines.

Various further and more specific objects, features and advantages of the invention will appear from the specification given below, taken in connection with the accompanying drawings, illustrating by way of example a preferred form of the invention.

In the drawings:

FIG. 1 is a schematic and plan view of an apparatus according to the invention;

FIG. 2 is a schematic and side elevational View taken along line 22 of FIG. 1;

FIG. 3 is a detailed section taken along line 33 of FIG. 1 showing the suction plates in open position and the welding unit in an inoperative position;

FIG. 4 is similar to FIG. 3, showing the suction plates in an approached but opened position and the welding unit in an operative position;

FIG. 5 is similar to FIG. 3 showing the suction plates in closed or face to face relation and the welding unit in an inoperative position;

FIG. 6 is an enlarged fragmentary view showing the plate support and actuating mechanism of FIG. 5;

FIG. 7 is an orthogonal view of FIG. 6;

FIG. 8 is a side view of the opening station;

FIG. 9 is a plan view of the suction plates in their approached but opened position;

FIG. 10 shows a bag blank having its end opened and secured by means of the apparatus of the present invention.

Referring now to the drawings, and in particular to FIGS. 1 and 2 there are seen to be provided a feeding device 1 comprising a feeding plate 2 for supporting tubular bag blanks A of a plastic sheet material such as polyvinyl chloride. These bag blanks are precut to the configuration shown and are provided at the ends thereof with longitudinal slits B for the formation of the corner and side flaps of the end closures. The blanks are to be opened in the machine by folding the upper layer of the end portions thereof about an end fold line which runs across the blank, shown at C. This separates the bag end into side flaps D (shown at the output) and corner flaps E which are secured or sealed to each other along side flap fold lines F parallel to the end fold line C. In conjunction with the feeding device 1 there is provided a bar 7 having a plurality of suction elements 7a which attach themselves to an individual blank and shift it to a sliding plate 3 positioned slightly downstream of the feeding device 1.

Associated with the sliding plate 3 are a pair of pincers 4 (FIG. 1), which grasp the blank and pull it off the suction elements 7a for transferral to an opening station indicated generally at 5. These pincers 4, which may be of conventional type, are connected to sliding chains (not shown) driven by a suitable motor (also not shown). The pincers 4 extend from the chains up through slots 6 in the sliding plate 3 so as to grasp the blanks A. The slots 6 are so disposed that the pincers 4 may grasp the blanks at points very close to the end fold lines C of the blanks. This serves to prevent distortion of the blank as it is transferred into the opening station.

Between the stationary plate 2 and the sliding plate 3 there are provided a plurality of air jets or nozzles 8 (FIG. 2) which direct a stream of air towards the lower end of each blank as it passes between the plates. This serves to prevent the rather limp blank from bending down and catching on the edge of the sliding plate 3 and thus becoming distorted.

The opening station 5 includes means for opening the side flaps of the tubular bag blanks and for securing the corner flaps to the under surfaces of the side flaps. The opening and securing operations carried out at the two ends of the tubular blank are identical and the description therefore will proceed only in connection with the forming of a bag closure at one end of the blank, the mechanisms for carrying out the operations at the other end being the same.

As shown in FIGS. 39, there is provided a frame 9 having an upper part 9' on which are disposed tWo vertical stanchions 10. At the free end of each stanchion 10 are provided a front connecting arm 12, and a transverse movement actuating arm 13 (FIG. 6), together keyed to a pin 20 on the stanchion. These arms are offset relative to each other by an angle on (FIG. 7). The free ends of the actuating arms 13 are connected by a rod element 14 which is linked at 15 to a piston rod 16 of a double acting hydraulic cylinder 18. The hydraulic cylinder is mounted by means of a support element 19 which projects from the upper part 9 of the frame 9'.

On the upper part 9 are further disposed two other vertical stanchions 21 (FIGS. 6 and 8) on the lower extremities of which are disposed two bearings 22 which support a shaft 23 in axial alignment with the pin 20. On the two ends of the shaft 23 are keyed inner crank arms 24. The protruding ends of each of these arms is interconnected by means of a crankpin 25 to the protruding end of an outer crankarm 26 which pivots about one of the pins 20. A pair of supports 27 (FIG. 8) are attached to the crankarms 26 and carry counterweights 28 to maintain rotational balance about the pins 20 and shaft 23.

On the inside ends of the pins 20 (FIGS. 6 and 8) are keyed gears 29 which rotate with the front connecting arms 12. These gears are meshed with intermediate gears 20 (FIG. 6) pivoted on the outer crankarms 26 intermediate its ends, as at 31. Additional gears 33 are keyed to bushings 32 (FIG. 6) on the crankpins 25 and rotate with rear connecting arms 34 which extend from the crankpins. The gears 33, like the gear 29 are cooperatively meshed with the reversing gears 30 so that their respective connecting arms pivot in synchronism relative to the crankarms 24 and 26.

A movable suction plate 36 is pivoted along its front edge to the lower ends of the front connecting arms 12 and along its rear edge to lower ends of the rear connecting rods 34, (FIG. 6). This plate, as shown in FIG. 9, has a flat suction surface provided with a plurality of suction holes 37 connected to a suitable vacuum pump (not shown) through pipes 11. The lower ends of the arms 12, are bent to an angle of about in order to facilitate the ejection of the tubular blanks A. The lower ends of the arms 12 are pivoted to the lower corners 36 and 36 of the plate 36 in alignment with its front edge while the lower ends of connecting rods 34 are pivoted to the upper corners 36 and 36 of the plate nearer its back edge. The longitudinal lower edge 36 of plate 36 (FIG. 8) is shaped to conform, when the plate 36 is in the operative position, to the centralpart of the sliding plate 3.

On the sliding plate 3 and disposed in cooperative relation to the movable suction plate 36 there is provided a stationary suction plate 38. This stationary suction plate 38 is provided with suction holes 39 (FIG. 9) asymmetrically disposed with respect to the suction 'holes 37 of the movable plate 36.

The stationary and movable suction plates 38 and 36 are each further provided with suitable electrodes 61 and 61 (FIG. 9) adapted to cooperate, as will be more fully described thereinafter, with a welding unit. These electrodes, as shown, extend along lines equally spaced from and parallel to the front edge of the movable plate 36.

To the shaft 23 (FIGS. 3, 6 and 8) is also keyed a gear 40, the teeth of which cooperate with a rack element 41 provided with an extension arm 42. The rack element 41 is guided within a guiding box 43 (FIGS. 6 and 8) which maintains the rack element in meshed relation with the gear 40. The free end 42' (FIGS. 3-5) of the extension arm 42 is pivoted to the upper end of a lever 44 which is freely pivoted to a shaft 45. The shaft 45 in turn is supported by means of suitable bearings 45', which are mounted on but disposed outside the frame 9 parallel to the shaft 23. The lower end of the lever 44 is provided with a roller bearing 44 which cooperates with a driving cam 46 keyed to the shaft 47. The shaft 47 is connected to a motor 50 (FIG. 8) through gears 48 and 49.

Laterally and in line with the stationary and movable suction plates 38 and 36 there is disposed a welding unit 70 comprising two electrodes 51 and 51' (FIGS. 3-5 and 8) which are longitudinally disposed with respect to the apparatus and supported by two electrode arms 52 keyed to the shaft 45. The electrodes 51 and 51' are mutually displaced at a distance substantially corresponding to the desired width of the bag bottom. This distance may be adjusted in any known manner. The electrodes cooperate, when in the operative position, with corresponding electrode 61 and 61' (FIG. 9) disposed on the suction plates 36 and 38. As can be seen in FIGS. 35, the length of the electrode arms 52 is such to bring the electrodes, when in the operative position, to cooperate with the plates 36 and 38. On the shaft 45 are also keyed element 53 (FIGS. 3-5 and 8) also provided with follower arms 54 on the ends of which are disposed cam rollers 55 which cooperate with a driving cam 56 keyed to the shaft 47.

On the electrode arms 52 at a position located between the electrodes 51 and 51' are disposed two spring supported elements 60 which protrude beyond the electrodes to act upon and hold the corner flaps secure in flattened condition when the electrode arm i brought dow nto welding position.

As previously stated, the opening station 5 is provided with two identical units each adapted to carry out the opening and securing operations at the opposite ends of the tubular bag blanks A. In order to adjust the apparatus for manufacturing bags having diflerent length, means, such as the turnbuckle 57 may be provided for widening or narrowing the distance between the two frames 9.

Suitable transferring means are provided to pick up the opened tubular element from the opening station 5 and to shift it to a subsequent collecting station 59 (FIG. 2).

The operation of the above described apparatus Will now be discussed.

A flattened tubular bag blank A is picked up by the suction elements 7 from the stationary plate 2 and is shifted to the sliding plate 3 where it is grasped by the pincers 4 near its end fold lines C and is transferred to the opening station 5. During transferral the movable suction plate 36 and the electrodes 51 and 51' are in their inoperative position shown in FIG. 3. When the bag blank has reached the opening station 5 the pincers 4 automatically release and the blank remains in proper position within the opening station 5 until all the end opening and securing operations are completed. The tubular blank is positioned within the opening station 5 in such a way that the end fold lines C about which the side flaps are folded lay along the front edge of the stationary plate 38.

The operation of the hydraulic cylinder 18 causes the rod 14 to move downwardly and accordingly to rotate the actuating arm 13 and the front connecting link 12. This rotation causes the movable plate 36 to shift translationally from its inoperative position as shown in FIG. 3 to a first stage position shown in FIG. 4. At this time the front edge of the movable plate 36 is positioned in closely aligned relation to the upper edge of the stationary plate 38 so as to effectively secure the bag blank along its end fold line C. The inclination of the movable plate 36 with respect to the central part of the sliding plate 3 is such to form a continuous plane with the stationary plate 38.

The lever/44, due to the action of the cam 46, then rocks inwardly, acting through the rack 41 and gear 40, to cause the shaft 23 to rotate in the direction of the arrow H (FIG. 3). The crank and connecting rod system 34, 35 causes the plate 36 to undergo rotational movement in the direction of the arrow K (FIG. 4) about its front edge. This rotation brings the plate 36 from its first stage position shown in FIG. 4 to a second stage position as shown in FIG. 5. Upon completion of this rotational movement the plate 36 lays face to face upon the stationary plate 38, and together with the stationary plate 38 envelops or sandwiches that portion of the blank A which extends above its end fold line C.

It will be appreciated that when the crank and connecting rod system are in upper dead center position during the rotation of the plate 36, it could easily reverse its direction and return to its original position as shown in FIG. 4 while the crankarms 24 and 26 continue to rotate in the same direction. However, the continued movement of the plate 36 in its proper direction is assured by means of the gears 29, 30 and 33 which cooperate with the linkages to direct the movements of the plate 36 along its prescribed path.

The width of the plates 36 and 38 is substantially equal to the width of the side flaps D of the tubular blank and, due to the action of the vacuum pump (not shown), the lower side flap is caused to adhere to and be maintained against the stationary plate 38 while the upper side flap is caused to adhere to the movable plate 36. As above stated, the suction holes 39 of the stationary plate 38 and the suction holes 37 of the movable plate 36 are offset relative to each other. This condition facilitates the opening of the side flaps when the plates are separated from each other. While the vacuum system is in operation, the lever 44 is rocked inwardly (in a direction opposite to its above described movement) by the cam 47. This causes the movable plate 36 to rotate again about its front edge in the direction of the arrow K (FIGS. 5 and 7) so as to open from the stationary plate 38 and return to the position shown in FIG. 4. During this opening operation of the plates, the lower side flap of thetubular element is held against the stationary plate 38 while the upper side flaps is held against and follows the movement of the plate 36. The upper side flap is thus rotated about the end fold line C with respect to the lower flap. Because of the particular configuration of the tubular bag blank, the opening of the side flaps causes the corner flaps to fold inwardly to assume. their desired position for the securing of welding operation.

The cam 56 in rotating acts upon the element 53, the shaft 45 and the electrode arms 52, and causes the electrodes 51 and 51' to move from their inoperative position in FIG. 3 to their operative position shown in FIG. 4; so that the electrodes are brought down along the side flap fold lines F (FIG. 10).

These electrodes cooperate with their corresponding '3' electrodes 61 and 61' disposed on the suction plates 36 and 38. During the downward movement of the welding unit, the spring mounted elements 60 press down on the corner flaps in order to keep them flat and steady until the welding operation is completed.

Suitable electric contacts are provided to connect the electrodes to an electrical power source when they are in their welding position. If desired, the electrodes may, as shown in the drawings, be constructed to supply heat along the full length of the side flap fold lines F (FIG. or they may be made shorter to operate along that portion of the fold lines corresponding to the overlapped areas of the corner flaps and side flaps.

The electric circuit for the electrodes may advantageously be connected with the vacuum gauge of the vacuum supply pump (not shown) through suitable microswitches arranged to disconnect the circuit when, for any reason, the positioning of the tubular bag blank over the plates is not correct.

At the end of the welding operation the electrodes are brought again in their inoperative position shown in FIG. 3; and the movable plate 36, due to the action of hydraulic cylinder 18 is moved back translationally by movement of the front connecting arms 12 to free the blank and allow the transferring means to shift the blank to the collecting station 59.

In those portions of the foregoing description which concern the structure and operation of the apparatus, the particulars relating to the specific means for effecting operation of the various cams and transferring means have not been shown as it would be obvious to anyone skilled in the art to provide means for achieving paper synchronization to obtain the required sequence of the operations.

What is claimed and desired to be secured by Letters Patent is:

1. Apparatus for automatically opening the ends of tubular bag blanks of a non-rigid non-creasable material, said apparatus comprising means for individually positioning the tubular b-ag blanks in a given attitude within an opening station, a pair of plates having fiat suction surfaces thereon, means mounting said lates for relative reciprocal movement from a first inoperative open position to a second operative closed position in which said suction surfaces are in face to face alignment against the opposite sides of one end of a bag blank positioned in said opening station, means operative to produce relative rotation of said plates about a common axis which passes across said bag blank to bring the suction surfaces thereof into a common plane whereby to produce relative outwardly folded side flaps and inwardly folded corner flaps from said bag blank, means for adhering the corner flaps along the marginal edges to the under surfaces of the side flaps, said adhering means comprising elongated heating elements mounted to move down toward the suction surfaces of said plates in their opened position with said heating elements being parallel to and equally displaced on either side of said common axis, and means to move the bags away from said opening station for transferral to a subsequent station.

2. Apparatus as described in claim 1 wherein said heating elements are mounted on an arm connected to a fixed pivot and further including holding elements resiliently mounted on said arm in proximity to said heating elements to protrude slightly beyond said heating element for holding down the corner fiaps of said blank during the sealing operation.

3. The apparatus described in claim 1 wherein said heating elements comprise electrodes which cooperate with correspondingly shaped and positioned electrodes on the suction surfaces of said suction plates.

4. Apparatus for automatically opening the ends of tubular bag 'blanks made of a non-rigid non-creasable material, said apparatus comprising means for individ ually positioning the tubular bag blanks in a given attitude within an opening station, a pair of plates having fiat suction surfaces thereon, means mounting said plates for relative reciprocal movement from a first inoperative open position to a second operative closed position in which said suction surfaces are in face to face alignment against the opposite sides of one end of a bag blank positioned in said opening station, means operative to produce relative rotation of said plates about a common axis which passes across said bag blank to bring the suction surfaces thereof into a common plane whereby to produce relative outwardly folded side flaps and inwardly folded corner flaps from said bag blank, means for adhering the corner flaps along the marginal edges to the under surfaces of the side flaps, between said feeding station and said opening station, a plurality of air nozzles constructed and arranged to direct a stream of air upwardly from below the plane of said blanks passing therebetween to prevent the ends of said blanks from passing downwardly between said stations and becoming distorted.

5. Apparatus for opening the side flap portions at one end of a plastic tubular bag blank for forming an end closure therefrom, said apparatus comprising means for securing a bag blank in a flattened extended position, a pair of plates having flat suction surfaces thereon, one of said plates being fixedly mounted to underlie said end of a bag blank secured in said flattened, extended position, with its suction surface contacting said blank, the other of said plates being mounted for separate translational and rotational movements, the path of said translational movement being above a 'bag blank secured in said position to bring the edge of said other plate against the upper surface of said blank along an end fold line extending across said blank, the path of said rotational movement being about said end fold line as an axis to bring the suction surfaces of said plates in face to face contact with the opposite sides of the end of said blank whereby their said suction surfaces cause adherence to opposite side flap portions of said blank, and means for reversing the rotational movement of said other plate to bring its said suction surface into a common plane with the suction surface of said one plate, said movable plate being suspended at either end thereof by means of a parallelogram type linkage mechanism, each said mechanism including a front connecting arm between a fixed pivot and a pivot on said movable plate aligned with its front edge, crank arm means mounted coaxially with but independently of said fixed pivot and a rear connecting arm between the outer end of said crankarm means and a rearward point on said movable plate, first drive means operable to rotate said front connecting arm about said fixed pivot to effect said translational movement and second, separate, drive means operable to rotate said crankarm to effect said rotational movement.

6. Apparatus according to claim 5 further including first and second gear means fixed, respectively, to rotate with each of said connecting arms relative to said crankarm means and an intermediate gear pivotally mounted on said crankarm means and meshed with both said first and second gear means for ensuring proper movement of said movable plate upon actuation of said second drive means.

7. In apparatus for manipulating the ends of tubular bag blanks for forming same into a configuration suitable for forming a closed end construction, the combination of a pair of end flap folding plates having surfaces capable of adhering the bag blank material, and mounting means for said plates, said mounting means being constructed to hold said plates in spaced apart, substantially coplanar relation, means arranged to actuate said mounting means to move said plates relative to each other in a given sequence, firstly in translation to bring their adjacent edges together on opposite sides of a flattened bag blank along an end flap fold line, secondly in rotation about said fold line to sandwich the end of said bag blank therebetween, thirdly in opposite rotation about said fold line to spread apart the diiferent layers of said bag blank for forming a configuration suitable for sealing and further folding and fourthly, in opposite translation to release said bag blank.

8. Apparatus as in claim 7 wherein one of said plates is stationarily mounted and wherein said mounting means comprises an articulated parallelogram linkage with the other of said plates forming one arm of said linkage, and means for separately controlling pivotal movements of the arm adjacent and the arm opposite said other plate, about their common pivot axis.

9. Apparatus as in claim 8 wherein the arms adjacent said other plate are gearably interconnected to maintain equal pivotal orientation with respect to said opposite arm.

References Cited UNITED STATES PATENTS 634,099 10/1899 Uhlmann 9328 2,224,656 12/1940 Robinson 9328 2,712,275 7/1955 Gramegna 93-28 10 BERNARD STICKNEY, Primary Examiner.

FRANK E. BAILEY, Examiner. 

1. APPARATUS FOR AUTOMATICALLY OPENING THE ENDS OF TUBULAR BAG BLANKS OF A NON-RIGID NON-CREASABLE MATERIAL, SAID APPARATUS COMPRISING MEANS FOR INDIVIDUALLY POSITIONING THE TUBULAR BAG BLANKS IN A GIVEN ATTITUDE WITHIN AN OPENING STATION, A PAIR OF PLATES HAVING FLAT SUCTION SURFACES THEREON, MEANS MOUNTING SAID PLATES FOR RELATIVE RECIPROCAL MOVEMENT FROM A FIRST INOPERATIVE OPEN POSITION TO A SECOND OPERATIVE CLOSED POSITION IN WHICH SAID SUCTION SURFACES ARE IN FACE TO FACE ALIGNMENT AGAINST THE OPPOSITE SIDES OF ONE END OF A BAG BLANK POSITIONED IN SAID OPENING STATION, MEANS OPERATIVE TO PRODUCE RELATIVE ROTATION OF SAID PLATES ABOUT A COMMON AXIS WHICH PASSES ACROSS SAID BAG BLANK TO BRING THE SUCTION SURFACES THEREOF INTO A COMMON PLANE WHEREBY TO PRODUCE RELATIVE OUTWARDLY FOLDED SIDE FLAPS AND INWARDLY FOLDED CORNER FLAPS FROM SAID BAG BLANK, MEANS FOR ADHERING THE CORNER FLAPS ALONG THE MARGINAL EDGES TO THE UNDER SURFACES OF THE SIDE FLAPS, SAID ADHERING MEANS COMPRISING ELONGATED HEATING ELEMENTS MOUNTED TO MOVE DOWN TOWARD THE SUCTION SURFACES OF SAID PLATES IN THEIR OPENED POSITION WITH SAID HEATING ELEMENTS BEING PARALLEL TO AND EQUALLY DISPLACED ON EITHER SIDE OF SAID COMMON AXIS, AND MEANS TO MOVE THE BAGS AWAY FROM SAID OPENING STATION FOR TRANSFERRAL TO A SUBSEQUENT STATION. 